docs: def execute_command(self):
          """
          Execute the shell command.
          """
          stderr = ""
          role_count = 0
          for role in utils.roles_dict(self.roles_path):
              self.command = self.command.replace("%role_name", role)
              (_, err) = utils.capture_shell("cd {0} && {1}".
                                             format(os.path.join(
                                                    self.roles_path, role),
                                                    self.command))
  
              stderr = err
              role_count += 1
  
          utils.exit_if_no_roles(role_count, self.roles_path)
  
          if len(stderr) > 0:
              ui.error(c.MESSAGES["run_error"], stderr[:-1])
          else:
              if not self.config["options_quiet"]:
                  ui.ok(c.MESSAGES["run_success"].replace(
                      "%role_count", str(role_count)), self.options.command)